Strengthening of non-conforming RC shear walls using different steel configurations

• Five reinforced concrete shear walls were tested as cantilevers under static cyclic loading.
• Four different strengthening configurations using steel straps and angles were applied.
• All strengthening configurations were able to control reinforcement buckling and shear cracking.
• Strengthened walls exhibited adequate values of ductility and energy dissipation.

The aim of the present paper is to examine the behavior of strengthened existing non-conforming reinforced concrete shear walls, namely shear walls which are designed and constructed according to older seismic codes non-compliant with modern earthquake design standards. A strengthening method using steel elements (straps and angles) is examined. For the purposes of the present study five shear walls – one reference and four strengthened – with shear ratio equal to 2.0, characterized as medium-rise, were designed and tested as cantilevers under static cyclic loading. The strengthened specimens included four different configurations, targeting each time to restrict the phenomenon of buckling of reinforcing bars under compression and control the cracking width along the web. The four strengthening configurations include only horizontal straps along the height, horizontal straps and corner angles along the height, horizontal straps and corner angles only in the lower part and, finally, combination of horizontal straps and corner angles in the lower part with bidiagonal (X shaped) configuration in the rest of the web.